1. Field of the Invention
The present invention relates to a method of measuring a blood component and a sensor used in the method.
2. Related Background Art
Conventionally, sensors for blood component measurement have been used for clinical test, self-measurement of blood glucose level by diabetics, etc. The configuration of the sensor for blood component measurement is such that, for example, a cover is disposed on an insulating substrate having a working electrode and a counter electrode on its surface, with a spacer intervening between the cover and the insulating substrate. On the working electrode and the counter electrode, a reagent containing an oxidoreductase, a mediator (an electron carrier), and the like is provided, thereby forming an analysis portion. The analysis portion communicates with one end of a channel for leading blood to the analysis portion. The other end of the channel is open toward the outside of the sensor so as to serve as a blood supply port. Blood component analysis (e.g., analysis of blood glucose level) using the sensor configured as above is carried out in the following manner, for example. First, the sensor is set in a dedicated measuring device (a meter). Then, a fingertip or the like is injured with a lancet to cause bleeding, and the blood supply port of the sensor is brought into contact with the blood that has come out. The blood is drawn into the channel of the sensor by capillary action and flows through the channel to be led to the analysis portion where the blood comes into contact with the reagent. Then, a redox reaction occurs between a blood component and the oxidoreductase so that a current flows via the mediator. The working electrode and the counter electrode detect the current, and the measuring device converts the detected current into an amount of the blood component and displays the value obtained by the conversion.
In the above-described manner, the sensor can measure the blood component. However, since the obtained measured value might be affected by a hematocrit (Hct), it might be necessary to remove the effect of Hct in order to obtain an accurate measured value. One example of a method of removing the effect of Hct is preparing a correction table beforehand using a sample with a known Hct and then correcting the measured value using this correction table (see JP 11(1999)-194108 A, for example). Another example is correcting a Hct using a parameter that has been set beforehand (see WO 02/44705, for example). However, these methods require a laborious correction process such as providing a correction table beforehand or performing a complicated calculation using a parameter.